Abrasive article



July 8, 1969 H. HAGELUKEN ETAL 3,453,782

Y ABBAsIvE ARTICLE Filed Jan. 10, 1967 United States Patent O 3,453,782 ABRASIVE ARTICLE Hubert Hageliiken, Dusseldorf, and Karl Held, Haan, Rhineland, Germany, assignors to Carl Kurt Walther, Walther-Technik, Wuppertal-Vohwinkel, Germany Filed Jan. 10, 1967, Ser. No. 608,401 Int. Cl. B24b 31/02; B02c 17/14 U.S. 'CL 51-164.5 6 Claims ABSTRACT OF THE DISCLOSURE An abrasive article for use in tumbler-type grinders and having a core of high specific weight surrounded by a resilient porous shell of lower specic weight with abrasive particles in a lubricating carrier filling the pores.

Background of the invention The present invention relates to polishing means in general, and more particularly to abrasive -bodies for use in tumbler-type grinding and polishing machines. Still more specifically, the invention relates to a novel abrasive body of the type just outlined.

It is known to surface-condition articles of manufacture by polishing or finely grinding their surfaces in tumblertype grinding apparatuses. This is accomplished by placing the articles to be treated into a rotating or oscillatlng drum or other container and intermixing them with abrasive bodies, and the relative movement which occurs between such bodies and the articles to be treated during rotation or oscillation of the container results in many sliding contacts between the surfaces of the articles to be treated and the surfaces of the abrasive bodies, whereby the desired grinding or polishing effect is obtained. However, the results derived thus far from this type of Surface treatment have not been entirely satisfactory because, if the abrasive body is merely coated on its surface, with a layer of abrasive material, this will wear off rather rapidly and render the abrasive bodies useless. On the other hand, if a somewhat porous material has been used as a carrier and the surface pores thereof have been filled with an abrasive substance, adequate contact between the thus embedded abrasive substance and the surfaces of the articles to be treated has usually been prevented by the surrounding material of the carrier. Obviously, `both of these situations are undesirable since they significantly impair the utility of this type of grinding or polishing process.

Summary of the invention In view of the disadvantages set forth above with respect to the prior art it is a general object of the present invention to overcome such disadvantages.

A more specific object of the invention is to provide a novel abrasive body, particularly for use in tumbler-type grinding and polishing machines.

Still a more specific object of the invention is to provide such a novel abrasive body whose abrasive action is considerably longer lasting than as heretofore known.

A concomitant object of the invention is to provide an abrasive body of the general type outlined which assures proper contact between the abrasive matter and the surfaces of the articles to be treated at all times.

In accordance with one feature of our invention we provide a novel article of manufacture of the type set forth above, which comprises at least one core member of a solid material having a relatively high specific weight. This core member is completely surrounded by a shell of porous material, and this latter material has a substantially lower specific weight than that of the solid material of the core member. Finally, the novel article further 3,453,782 Patented July 8, 1969 comprises an abrasive mass, and this includes solid particles of abrasive material which are received in at least some pores of the porous material at the outer surface of the shell, and fill these pores.

The novel features which are considered as characteristic for the invention are set forth in the :appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of Specific embodiments when read in connection with the accompanying drawings.

Brief description of the drawing FIG. l is a sectional elevation of our novel article of manufacture, in one possible embodiment thereof;

FIG. 2 is a partly sectioned perspective view of the components utilized for the manufacture of a plurality of articles of the type shown in FIG. 1, in semi-assembled state; and

FIG. 3 shows a novel article of manufacture of the type set forth herein, in a view similar to FIG. 1, but in a differembodiment.

Description of the preferred embodiments Discussing now the drawing in detail, and iirst FIG. 1 thereof, it will be seen that the article shown therein, which will hereafter be referred to as the abrasive body, comprises a core 1 which is surrounded by a shell 2. The shell 2 consists of a porous material which may for instance be felt, foam rubber or a foamed synthetic plastic material, such polyurethane foam. These materials of course have a relatively low specic weight and are selected in accordance with the invention to have a certain capacity for yielding under pressure. It is to be noted that all of the materials indicated as suitable are of the opencell type.

The core 1 is preferably spherical, as indicated in the drawing, and consists of a material having a much higher specific weight than the specific weight of the shell 2. Various materials are, of course, suitable for this purpose and among these are lead, zinc, and steel although this is by no means an exhaustive recitation.

The open pores adjacent the surface of shell 2 are filled 'with an abrasive mass, and again many different well known materials are suitable. Among these are particles of aluminum oxide, zirconium carbide, zirconium oxide, ground pumice, emery and the like. The particular size selected for the individual particles depends largely upon the type of grinding or polishing which is to be performed with the finished abrasive body, but it will be obvious that the individual particles must be small enough to be accommodated in the pores of the material from which shell 2 is constructed. To bind these particles and to prevent them from falling out of the pores of shell 2, as well as to provide a certain lubricating action on the surface of the articles which are to be polished, the particles of abrasive material are dispersed in a carrier of fat or wax. For this purpose, again, many substances are well known and suitable and such substances may be of synthetic origin, or may be derived from plants or animals. Furthermore, mixtures thereof can also be used for this purpose. Advantageously, the abrasive mass consisting of the fat or wax and the particulate abrasive material dispersed therein, is provided in liquid form or as a paste and the shell 2 is impregnated therewith.

It is to be noted that the core 1, which can of course also consist of more than a single member, serves not only to provide weight for the novel abrasive body, but has another and even more important purpose. As has been mentioned above, the materials used for the shell 2 are capable of yielding under pressure, that is they have a certain elasticity. Now obviously, when an abrasive body, such as that shown in FIG. 1 tumbles with a mass of similar bodies and articles which are to be treated in a rotating or oscillating container, pressure will be exerted on it by the other bodies and articles in the container Whenever it comes in contact with these. An elastic material capable of freely yielding would be compressed to a significant degree, and would in many instances conform itself to spaces existing between the other bodies and articles which surround it and press upon it. This Would clearly be detrimental to the desired abrasive action. In the novel abrasive body, according to the present invention, this is not the case. Rather7 pressure exerted upon the shell 2 from any side will be resisted by the core 1 embedded in the shell so that the material of the shell will be compressed against the core 1 in that area at which pressure is being exerted externally against the shell 2. This causes the material of the shell 2 which surrounds the quantities of abrasive mass embedded in the various surface pores to recede inwardly, so that the particulate abrasive material carried by the solidified fat or wax rises above the surface of the shell 2 in that area at which pressure is exerted. This action is enhanced by the presence in these pores of the fat or wax which of course promotes free sliding movement of the material of shell 2 relative to the quantities of wax or fat and the abrasive particles embedded therein. Thus, unobstructed contact of the abrasive particles with the surface of the article pressing against the surface of shell 2 is assured and proper abrading or polishing of this surface can take place.

The decided advantages of the invention will be obvious if it is considered that the material of shell 2, because of its capacity for yielding under pressure, is able to conform to at least some extent to the contours of the article which presses against the shell. Furthermore, the repeated exertion of such pressure and subsequent relief which occur from the many contacts .of each of the abrasive bodies with the articles to be treated during rotation or oscillation of the container of the tumbler-type grinding or polishing machine, results in what might be considered a pumping action. During each exposure of the abrasive mass consisting of fat or wax and abrasive particles embedded therein, some of this mass is of course destroyed by contact with the article or articles to be treated and is carried away thereby. The pumping action just mentioned assures, however, that the entire quantity of this abrasive mass contained in the various pores of the shell 2, is eventually brought to the surface and thus available for the desired abrasive action. Thus, there is no loss of the abrasive mass as would occur if the pumping action where not present in which case only the rather small quantity of abrasive mass immediately at the surface of the shell 2 would be available for the abrasive action and, once used up, the remainder of the abrasive mass deeper in the respective pores would be wasted. Furthermore, it is also to be mentioned that the ability of the material of shell 2 to yield, as well as the similar ability of the abrasive mass, assures that the surfaces of the articles to be treated are not subjected to undue abrasive action resulting in the formation of undesirable grooves or scratches, as Would be the case if neither the abrasive mass nor the material of shell 2 were capable of yielding to pressure.

While in the novel abrasive body all of the abrasive mass used for impregnating the pores of the shell 2 will be completely used up, the material of shell 2 itself is subject to relatively little destructive force and will therefore last quite a considerable period of time. In this connection it should be noted that the presence of the Wax or fat in which the abrasive particles are embedded serve-s to reduce friction against the material of the shell 2 surrounding the individual pores so that little or no damage is done to such material during the aforementioned pumping action. It will thus usually be possible to reimpregnate the shell 2 with the abrasive mass when the quantity of such abrasive mass introduced during a preceding impregnation has been used up.

FIG. 3 shows by way of example that other configurations are possible for the novel abrasive body; whereas in FIG. l there was shown a cube, FIG. 3 shows a sphere in which the core designated with reference numeral 11 and the shell is designated with reference numeral 22.

FIG. 2 shows a -simple and practical way of manufacturing the novel abrasive bodies in accordance with the present invention. Advantageously, two plate-shaped members 2' consisting of the material selected for the shell 2 are provided with recesses 3. In the embodiment illustrated the core members 1 are shown to be spherical and thus the recesses 3 in the respective plates 2 are shown to be of hemi-spherical configuration so that, when the two plates 2 are placed together into face-to-face contact, cooperating hemi-spherical recesses in the respective plates 2 will together form a spherical recess. Of course, other configurations or arrangements can be selected and this is shown by way of example only.

The spherical core members 1 are placed into the hemi-spherical recesses 3 of one of the plates 2 and it will be seen that a great many of such recesses are provided, each of which can accommodate one of the core members 1. Thereupon, the other plate 2 is placed on top of the first plate and two are joined together in a suitable manner, for instance by bonding their engaging faces to one another. Subsequently, and if it is desired to provide an abrasive body of the configuration shown in FIG. l, the composite consisting of the plates 2' and the core members 1 embedded between them is severed along the dashed lines and it will be obvious that this will result in cube-shaped bodies, similar to that shown in FIG. l, each of which contains one of the core members 1 in its interior. Thereupon, the individual abrasive bodies are then impregnated with the abrasive mass described earlier and, when the fat or wax which serves as carrier of the abrasive mass has solidified, the abrasive bodies are ready for use.

Of course, the examples which have been given herein are strictly for illustrative purposes only and many modifications will offer themselves to those skilled in the art. For instance, it is by no means necessary to construct the individual abrasive bodies in the manner shown in FIG. 2; rather the shell 2 can be provided on the core members 1 by appling a suitable material in form of a flock as long as the resulting ock has the requisite properties set forth above. In particular, such a manner of producing the novel abrasive bodies can be used if it is desired to construct bodies of irregular outline.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of abrasive bodies, differing from the types described above.

While the invention has been illustrated and described as embodied in abrasive bodies for use in tumbler-type grinding or polishing machines, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so f-ully reveal the gist of the present invention that others can, by applying current knowledge readily adapt it for various applications, without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is set forth in the appended claims.

We claim:

1. An abrasive article comprising, at least one core member of a solid material having a relatively high specific Weight; a shell of porous material having a substantially lower specific weight completely surrounding said core member and being at least slightly yieldable under pressure; and an abrasive mass including solid particles of abrasive material received in and filling at least some pores of said porous material at the outer surface of said shell.

2. An article as defined in claim 1, wherein said porous material is an open-celled synthetic plastic material.

3. An article as dened in claim 1, wherein said abrasive mass comprises a carrier substance in which said particles are disposed.

4. An article as defined in claim 1, wherein the absolute Weight of said core member and said shell are substantially equal.

5. An article as described in claim 3, wherein said carrier substance is wax.

6 6. An article as described in claim 3, wherein said 5/1931 Carnahan 241-84 X 5/1962 Cadwell 241-184 OTHER REFERENCES German printed application, 1,071,451, December 1959.

HAROLD D. WHITEHEAD, Primary Examiner.

U.S. Cl. XR. 

